From fa391d1267f707abe8d770d383fd3eebe56e490d Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Tue, 17 Oct 2023 21:35:37 +0200
Subject: [PATCH] Scheduler: torture test the thread access logic

Ensure the GroomingToken mechanism indeed creates an
exclusive section protected against concurrent corruption:

Use a without / with-protection test and verify
the results are exact vs. grossly broken
---
 .../vault/gear/scheduler-commutator-test.cpp  | 56 ++++++++++++++++++-
 wiki/thinkPad.ichthyo.mm                      | 32 +++++++++--
 2 files changed, 82 insertions(+), 6 deletions(-)

diff --git a/tests/vault/gear/scheduler-commutator-test.cpp b/tests/vault/gear/scheduler-commutator-test.cpp
index cc8b98f0c..c2adf62c4 100644
--- a/tests/vault/gear/scheduler-commutator-test.cpp
+++ b/tests/vault/gear/scheduler-commutator-test.cpp
@@ -28,14 +28,18 @@
 #include "lib/test/run.hpp"
 #include "activity-detector.hpp"
 #include "vault/gear/scheduler-commutator.hpp"
+#include "lib/test/microbenchmark.hpp"
 #include "lib/time/timevalue.hpp"
 #include "lib/format-cout.hpp"
 //#include "lib/util.hpp"
+#include "lib/test/diagnostic-output.hpp"///////////////////////////TODO TOD-Oh
 
 //#include <utility>
 #include <thread>
+#include <chrono>
 
 using test::Test;
+using lib::test::threadBenchmark;
 //using std::move;
 //using util::isSameObject;
 
@@ -47,6 +51,14 @@ namespace test {
 //  using lib::time::FrameRate;
 //  using lib::time::Offset;
   using lib::time::Time;
+  using std::this_thread::yield;
+  using std::this_thread::sleep_for;
+  using std::chrono_literals::operator ""us;
+  
+  namespace {// Test parameters
+    const size_t NUM_THREADS = 20;
+    const size_t REPETITIONS = 100;
+  }
   
   
   
@@ -65,6 +77,7 @@ namespace test {
         {
           demonstrateSimpleUsage();
           verify_GroomingToken();
+          torture_GroomingToken();
           verify_DispatchDecision();
           verify_findWork();
           verify_postDispatch();
@@ -95,8 +108,8 @@ namespace test {
       
       
       
-      /** @test TODO verify logic to control concurrent execution 
-       * @todo WIP 10/23 🔁 define ⟶ ✔ implement
+      /** @test verify logic to control concurrent execution
+       * @todo WIP 10/23 ✔ define ⟶ ✔ implement
        */
       void
       verify_GroomingToken()
@@ -115,6 +128,45 @@ namespace test {
       
       
       
+      /** @test ensure the GroomingToken mechanism indeed creates an
+       *   exclusive section protected against concurrent corruption.
+       * @todo WIP 10/23 ✔ define ⟶ ✔ implement
+       */
+      void
+      torture_GroomingToken()
+        {
+          SchedulerCommutator sched;
+          
+          size_t checkSum{0};
+          auto pause_and_sum = [&](size_t i) -> size_t
+                                  {
+                                    auto oldSum = checkSum;
+                                    sleep_for (500us);
+                                    checkSum = oldSum + i;
+                                    return 1;
+                                  };
+          auto protected_sum = [&](size_t i) -> size_t
+                                  {
+                                    while (not sched.acquireGoomingToken())
+                                      yield();
+                                    pause_and_sum(i);
+                                    sched.dropGroomingToken();
+                                    return 1;
+                                  };
+          
+          threadBenchmark<NUM_THREADS> (pause_and_sum, REPETITIONS);
+          
+          size_t brokenSum = checkSum;
+          checkSum = 0;
+          
+          threadBenchmark<NUM_THREADS> (protected_sum, REPETITIONS);
+          
+          CHECK (brokenSum < checkSum);
+          CHECK (checkSum = NUM_THREADS * REPETITIONS*(REPETITIONS-1)/2);
+        }
+      
+      
+      
       /** @test TODO verify the decision logic where and when
        *        to perform the dispatch of an Scheduler Activity chain.
        * @todo WIP 10/23 🔁 define ⟶ implement
diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm
index ce3eef930..59055f8cb 100644
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@@ -86130,13 +86130,37 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 <node BACKGROUND_COLOR="#eef0c5" COLOR="#990000" CREATED="1697560628310" ID="ID_670606112" MODIFIED="1697562328081" TEXT="demonstrateSimpleUsage">
 <icon BUILTIN="pencil"/>
 </node>
-<node BACKGROUND_COLOR="#eef0c5" COLOR="#990000" CREATED="1697560505486" ID="ID_1321080717" LINK="#ID_409935766" MODIFIED="1697567781570" TEXT="verify_GroomingToken">
-<icon BUILTIN="pencil"/>
+<node COLOR="#338800" CREATED="1697560505486" ID="ID_1321080717" LINK="#ID_409935766" MODIFIED="1697571165841" TEXT="verify_GroomingToken">
+<icon BUILTIN="button_ok"/>
 <node COLOR="#338800" CREATED="1697567790616" ID="ID_1691764279" MODIFIED="1697567807166" TEXT="API-Reaktion direkt im aktuellen Thread verifizieren">
 <icon BUILTIN="button_ok"/>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1697567807797" ID="ID_727144222" MODIFIED="1697567830467" TEXT="Multithread-Exclusion pr&#xfc;fen">
-<icon BUILTIN="flag-yellow"/>
+<node COLOR="#338800" CREATED="1697567807797" ID="ID_727144222" MODIFIED="1697571095208" TEXT="Multithread-Exclusion pr&#xfc;fen">
+<icon BUILTIN="button_ok"/>
+<node CREATED="1697570731407" ID="ID_1686773037" MODIFIED="1697570736338" TEXT="mit / ohne Test"/>
+<node CREATED="1697570737358" ID="ID_1684442461" MODIFIED="1697571093390" TEXT="microbenchmark verwenden">
+<icon BUILTIN="idea"/>
+</node>
+<node CREATED="1697570844041" ID="ID_744923834" MODIFIED="1697570856555" TEXT="100 Wiederholungen in 20 Threads"/>
+<node CREATED="1697570748133" ID="ID_1723527988" MODIFIED="1697571093396" TEXT="Ergebnisse sind sehr deutlich">
+<richcontent TYPE="NOTE"><html>
+  <head>
+    
+  </head>
+  <body>
+    <ul>
+      <li>
+        ohne Schutz braucht die Operation &#8709; 600&#181;s (bei 500&#181;s Schlafpause) und die Checksumme ist viel zu klein (~6000 statt wie erwartet 99000)
+      </li>
+      <li>
+        mit Schutz braucht die Operation im Schnitt 10ms und die Summe 0...N-1 stimmt exakt
+      </li>
+    </ul>
+  </body>
+</html>
+</richcontent>
+<icon BUILTIN="list"/>
+</node>
 </node>
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1697560511607" ID="ID_764686457" MODIFIED="1697560620825" TEXT="verify_DispatchDecision">